Hi all, I started with a simple problem: one of the old lead-acid batteries on our MkI finally died this year. The last evidence of a power plan update (other than new batteries) that I can deduce was pre-2001'ish with a poorly executed gummy-plug and amp meter edit.

My initial plan was conservative: replace it with an AGM or TPPL battery and repurpose my existing oversized lead-acid “start” battery as part of the house bank. Correct/update wiring as required. Then I realized AGM/TPPL pricing was close to (or the same as) many LiFePO4/LFP options… and now I’m deep in the rabbit hole looking at an inverter/charger setup (ex: Victron MultiPlus-II 12/3000/120-50), plus the other supporting bits and wholesale rewiring.

Before I buy anything, I’d love to learn from people who have already installed these:

1. Where did you mount your inverter/charger? (nav station, under settee, aft berth, near batteries, locker, etc.) Photos would be awesome.
2. Why that location? (DC cable length to batteries, AC wiring to panel, ventilation/heat, noise, dry/corrosion-safe, service access)
3. Any Catalina 36 Mk1-1.5 “gotchas”? Clearance, mounting structure, access to fuses/switches, routing heavy DC cables, etc. Universal truths (a.k.a Dohs!) are welcome too.
4. If you did it again today in 2026, what would you do differently? (different location, smaller/larger unit, separate inverter + charger, different battery placement, more ventilation/access, etc.)

Not looking to start a brand debate, mainly trying to avoid mounting a heavy, potentially loud unit somewhere I’ll regret later.

Thanks!